Plasma display panels provide screen displays by using ultraviolet rays generated by gas discharge so as to excite and illuminate phosphors.
Plasma display devices with such plasma display panels are of high display quality because of their higher speed display, wider angle of vision, and easier upsizing than display devices with liquid crystal panels, and also of being a self luminescence type and of other advantageous features. For this reason, of various flat panel display devices, plasma display devices have been drawing particular attention in these days and widely used, for example, as public display devices at spaces where many people gather or as domestic display devices for enjoying large screens at homes.
Plasma display panels are classified into an AC type and a DC type as driving mode, and are classified into a surface discharge type and an opposed discharge type as discharge mode. From the viewpoint of achieving higher definition, a larger screen size and a simpler structure, surface discharge type AC plasma display panels having a three-electrode structure are going mainstream. An AC plasma display panel is formed of a front plate and a back plate. The front plate includes a front substrate which is a glass substrate, a display electrode which is provided on the front substrate and which consists of a scan electrode and a sustain electrode, and a first dielectric layer which covers the display electrode. On the other hands, the back plate includes a back substrate which is a glass substrate, a plurality of data electrodes which are formed on the back substrate and which are orthogonal at least to the display electrode, and a second dielectric layer which covers the data electrodes. The front plate and the back plate are disposed to face each other so as to form discharge cells at the intersections of the display electrode and the data electrode, and to provide phosphor layers inside the discharge cells.
In the structure of such a plasma display panel, the process of forming the first dielectric layer and/or the second dielectric layer is disclosed, for example, in “2001 FPD Technology Outlook” published by Electronic Journal, Oct. 25, 2000, pp. 594-597. According to this forming process, dielectric paste containing a powdered glass material with a low melting point is applied by screen printing or die coating, then dried, and sintered.
However, plasma display panels with the aforementioned structure have a problem that withstand voltage disadvantages may occur when a driving voltage is applied to the display electrode or the data electrodes, thereby making it impossible to provide an excellent screen display. The withstand voltage disadvantages result from exfoliating, cracking, or chipping developing in the first dielectric layer and/or the second dielectric layer. These exfoliating, cracking, and chipping are considered to be caused by the presence of regions including angular parts at the peripheries of the first and/or second dielectric layers which have been formed on the glass substrates for covering the electrodes. In such a case, for example in a firing process in the production of these dielectric layers, the difference in thermal expansion between the dielectric layers and the glass substrate which is to be the front substrate or the back substrate causes the concentration of stress in the regions including the angular parts. As a result, exfoliating, cracking or chipping occurs in the dielectric layers starting from the angular parts. Even if exfoliating, cracking, or chipping does not occur during the firing process, stress is concentrated on the angular parts after the firing process, so that exfoliating, cracking or chipping is caused by external vibration or impact starting from the angular parts. As a result, withstand voltage disadvantages occur.
The present invention has been contrived in view of this situation, and has an object of achieving a plasma display panel capable of creating an excellent screen display by providing dielectric layers having a reduced occurrence of disadvantages such as exfoliating, cracking, and chipping.